APW7071 White LED DC/DC Step-Up Converter Features General Description • 2.4V to 6V Input Voltage Range • • 400mA, Internal Switch Current Up to 1MHz Switching Frequency • 70µA Typical No Load Quiescent Current • 0.1µA Typical Shutdown Current • • • Internal Soft-start Available in a Tiny 6-Pin SOT-23 Package Up to 87% efficiency The APW7071 is a high frequency step up DC/DC converter in a small 6 leads SOT-23 package specially designed to drive white LEDs with a constant current. The device can drive up to 4 LEDS in a series from one Li-Ion cell. The APW7071 is ideal for LCD panels requiring low current and high efficiency as well as white LED applications for cellular phone backlighting. • Operating Output Capacitor down to 0.1µF • • Over Voltage Protection included Lead Free Available (RoHS Compliant) Package Pin Out V IN Applications • Cellar Phones White LED Back Light • • • PDAs, Handheld Computers Digital Still Cameras MP3 Players • GPS Receivers OVP SHDN 6 5 1 2 4 3 SW GND FB SOT-23-6 (Top View) APW7071 Ordering and Marking Information APW7071 Package Code C : SOT-23-6 Operating Junction Temp. Range E : -40 to 85°C Handling Code TU : Tube TR : Tape & Reel Lead Free Code L : Lead Free Device Blank : Original Device Lead Free Code Handling Code Temp. Range Package Code APW7071 C : W71X XXXXX - Date Code Notes: ANPEC lead-free products contain molding compounds/die attach materials and 100% matte in plate termination finish; which are fully compliant with RoHS and compatible with both SnPb and lead-free soldiering operations. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J STD-020C for MSL classification at lead-free peak reflow temperature. ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and advise customers to obtain the latest version of relevant information to verify before placing orders. Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 1 www.anpec.com.tw APW7071 Block Diagram OVP(5) Under Voltage Lockout VIN(6) Thermal Shutdown SW(1) OVP + 400ns Min. off-time Error Comparator FB(3) + Vref=0.25V Control Logic 6us Max. on-time Gate Driver N-MOSFET Current Limit + - RSENSE Soft start SHDN(4) GND(2) Pin Description No Name 1 SW 2 GND 3 FB 4 SHDN 5 OVP 6 Vin Function Switch Pin. Connect to inductor/diode here. Minimize trace area at this pin to educe EMI. Ground Pin. Feedback Pin. Reference voltage is 0.25V. Connect cathode of lowest LED and resistor here. Calculate resistor value according to RFB = 0.25V/l LED Shutdown Pin. Tie to 1.3V or higher to enable device, 0.4V or less to disable. Over voltage protection sense pin. Connect this pin to VOUT for over voltage protection. Supply voltage Pin. Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 2 www.anpec.com.tw APW7071 Absolute Maximum Ratings Symbol Vin FB SHDN SW TJ TSTG Parameter Supply voltage Feedback Voltage Shutdown Voltage Switch Voltage Junction Temperature Range Storage Temperature Range Rating 7 7 7 20 150 -40 to +150 Unit V V V V °C °C Recommend Operating Conditions Symbol Vin Vsw L Cin Cout Ta Tj Parameter Min. 2.4 Vin Input supply voltage Switch voltage Inductor Input capacitor Output capacitor Operating ambient temperature Operating junction temperature Value Typ. Unit Max. 6.0 18 V V µH µF µF °C °C 4.7 4.7 0.1 -40 -40 85 125 Electrical Characteristics VIN=2.4V, EN=VIN, TA=-40°C to +85°C, typical values are at TA=+25°C (unless otherwise noted) Symbol Parameter Test Condition Supply Voltage and Current Vin Input Voltage Range Iq Isd UVLO Operating quiescent current Shutdown current Under-Voltage Lockout threshold Under-Voltage Lockout hysteresis ENABLE VIH SHDN high level input voltage VIL SHDN low level input voltage Ii SHDN input leakage current Power Switch and Current limit Vsw Maximum switching voltage toff Minimum off-time ton Maximum on-time Rds,on ILIM MOSFET on-resistance MOSFET leakage current MOSFET current limit Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 Min. APW7071 Typ. Max. 2.4 Iout=0, not switching, VFB=0.3V SHDN=GND 6 V 70 90 µA 0.1 1 2.3 µA V 2.1 100 mV 1.3 0.1 0.4 1 V V µA 350 4 400 6 20 500 7.5 V ns µs 350 600 1 400 1000 10 450 mΩ µA mA SHDN=GND or VIN Vin=2.4V, Isw=200mA Vsw=20V 3 Unit www.anpec.com.tw APW7071 Electrical Characteristics (Cont.) Symbol Parameter OUTPUT Vout IFB VFB Test Condition Min. Adjustable output voltage range Feedback input bias current VFB=0.3V 2.4≦VIN≦6.0V Feedback trip point voltage OVP threshold OVP hysteresis APW7071 Typ. Max. Vin 0.237 16 5 0.25 17 6 Unit 18 1 0.263 18 7 V µA V V V Typical Application Circuit D1 MSCD052 L1 Vin Vout 4.7µH 2.7V~6V C1 4.7µF 6 VIN SW 1 C1 4.7µF 6 VIN SW 1 off on GND 4 SHDN OVP FB 5 2 3 off on Fig.1 Typical 4LED application Rev. A.1 - Feb., 2006 GND 4 SHDN OVP FB 5 3 R1 13 R1 13 Copyright ANPEC Electronics Corp. C2 1µF 0.1µF 2 Vout 10µH 2.4V~6V C2 D1 MSCD052 L1 Vin Fig.2 4LED application with lower output voltage ripple 4 www.anpec.com.tw APW7071 Typical Characteristics (Circuit of Figure 1, VIN = 3.3V, ILED = 15mA, L1 = 4.7µH, CIN = 4.7µF, COUT = 0.1µF,4 LEDs, TA = +25°C, unless otherwise noted.) Efficiency vs LED Current Efficiency vs Supply Voltage 90 90 88 88 Efficiency(%) Vin=4.2V 86 Efficiency(%) Vin=3.6V 84 Vin=2.7V 82 86 84 82 80 78 80 76 78 74 ILED=15mA 76 72 74 70 0.1 1 10 100 2 3 LED Current(mA) 4 5 6 Supply Voltage(V) Switch Rds,on vs Supply Voltage Switch Rds,on vs Temperature 0.7 0.6 0.6 0.5 Rds,on(Ω) Rds,on(Ω) 0.5 0.4 0.3 0.4 0.3 0.2 0.2 0.1 0.1 Vin=3.3V Ta=25°C 0 -40 0 2 3 4 5 6 Rev. A.1 - Feb., 2006 0 20 40 60 80 100 Temperature(°C) Supply Voltage(V) Copyright ANPEC Electronics Corp. -20 5 www.anpec.com.tw APW7071 Typical Characteristics (Cont.) Non-Switch Quiescent Current vs. Supply Voltage Non-Switch Quiescent Current vs. Temperature 80 Non-Switch Quiescent Current(µA) Non-Switch Quiescent Current(µA) 75 70 65 60 55 50 45 Ta=25°C 40 2 3 4 5 6 75 70 65 60 55 Vin=3.3V 50 -40 -20 0 20 40 60 80 100 Temperature(°C) Supply Voltage(V) Start-up Waveform LED Current vs. Supply Voltage LED Current(mA) 25 20 SHDN 2V/DIV 15 VOUT 5V/DIV 10 Input Current 100mA/DIV L=4.7µH 5 Cout=0.1µF 4LED 0 1 2 3 4 5 6 1 ms/DIV Supply Voltage(V) Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 6 www.anpec.com.tw APW7071 Typical Characteristics (Cont.) PFM Operation OVP Waveform VOUT(AC) 200mV/DIV VOUT 5V/DIV Vsw 10V/DIV VFB 100mV/DIV 1 µs/DIV 20 ms/DIV Burst Mode Operation VOUT(AC) 200mV/DIV Vsw 10V/DIV VFB 100mV/DIV 2 µs/DIV Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 7 www.anpec.com.tw APW7071 Function Descriptions OPERATION Over Voltage Protection (OVP) The APW7071 operates in a pulse frequency modulation (PFM) scheme with constant peak current control.The operation can be understood by referring to the block diagram of Figure 1. The converter monitors the output voltage, and if the feedback voltage falls below the reference voltage (typical 0.25V), the internal switch turns on and the inductor current ramps up. The switch turns off if the inductor current reaches the internally set peak current (typical 400mA) or maximum on-time detected. As the switch is turned off, the inductor current ramps down to zero and charge output capacitor through external Schottky diode. The switch remains off for a minimum of 400 ns (typical), or until the feedback voltage drops below the reference voltage again. The operation frequency is up to 1MHz and is determined by the output current, current limit, inductor value, input voltage and output voltage. This regulation scheme is inherently stable, allowing a wider selection range OVP is integrated to prevent the output voltage increase over the maximum switching voltage rating. In some cases an LED may fail, this will result in the feedback voltage always being zero. The device will boost the output voltage higher and higher. When the output voltage exceeds the OVP threshold voltage (typical 17V), the switch turns off. The converter switch remains off until the output voltage falls below the OVP threshold voltage. Thermal Shutdown A thermal shutdown function is integrated to shutdown device when junction temperature exceed 160°C. If thermal shutdown detected, converter switch turn off until junction temperature falls bellow 120°C. for the inductor and output capacitor. Enable Force SHDN pin greater than 1.3 V to enable the device works in normal operation. Pulling SHDN pin less than 0.4V to shut down reducing the shutdown current to 0.1 µA (typical). The SHDN pin should not be left floating. Soft Start The APW7071 limits this inrush current by increasing the current limit at start-up. Under Voltage Lockout Transients during powering on or instantaneous glitches in the supply voltage can cause system damage or failure. The undervoltage lockout circuit turned the main switch off to prevent malfunction at low input voltage. Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 8 www.anpec.com.tw APW7071 Application Information Setup the LED current The LED current is controlled by the reference voltage and resistor and R1 shows in Figure 1. The Vin C1 4.7µF 6 2 a. By an adjustable DC voltage Uses a DC voltage to control the feedback voltage. As the DC voltage increases, current starts flowing down R3, R2 and R1. The loop will continue to regulate the feedback voltage at 250mV. Thus the current has to decrease through the LEDs by the same amount of current as is being injected from the DC voltage source. With a VDC from 0V to 3. 3V, the resistor values shown for R2 and R3 can 100Hz~300Hz PWM brightness control D1 MSCD052 L1 6 VIN GND 4 SHDN R1 13 c. By a filtered PWM signal Brightness can be achieved by a filtered PWM signal. The PWM signal above 5KHz is recommended. Vout D1 MSCD052 L1 Vin C2 1 3 FB signal apply to SHDN C1 4.7µF 6 VIN SW C2 1 0.1µF 2 GND OVP 4 SHDN FB 0.1µF 5 2 GND 4 R2 3 SHDN R3 120K Vout 4.7µH 2.7V~6V SW 5 OVP Fig. 4 Brightness Control by a PWM 4.7µH 2.7V~6V C2 1 SW Duty=100%, LED=20mA Duty=0%, LED off control the LED current from 0mA to 20mA. C1 4.7µF VIN 0.1µF Brigtness control Vin Vout 4.7µH 2.7V~6V current through the LEDs is given by the 250mV/R1. D1 MSCD052 L1 OVP FB 10K R1 13 3.3V PWM brightness 0V control Duty=100%, LED off Duty=0%, LED=20mA Vadj=3.3V, LED off Vadj=0V, LED=20mA Fig. 3 Brightness Control by an adjustable DC voltage 5 3 R2 10K R3 120K R4 10K R1 13 C3 0.1uF Fig. 5 Brightness Control by a filtered PWM signal b. By a PWM signal apply to SHDN The PWM signal is applied to the SHDN pin of the APW7071. The LEDs will switch between full load to completely shut off. The average current through the LEDs will increase proportionally to the duty cycle of the PWM signal. Due to the soft start function, the PWM signal should be 100Hz to 300Hz. Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 9 www.anpec.com.tw APW7071 Application Information (Cont.) Inductor selection Since the PFM peak current control scheme is inherently stable, the inductor value does not affect the stability of the regulator. The selection of the inductor together with the nominal load current, internal set peak current, input and output voltage of the application determines the switching frequency of the converter. For the LED application, inductor values between 2.2 µH up to 10 µH are recommended. Recommended inductors Part No. LQH32CN4R7M23L Value(µH) 4.7 Recommended output capacitor Part No. Value GRM185R61C105KE44D 1.0µF/X5R/ 0603/16V Any 0.22µF Any 0.1µF Vender Murata Any Any Input capacitor selection For good input voltage filtering, low ESR ceramic capacitors are recommended. A 4.7µF ceramic input capacitor is sufficient for most applications. For better input voltage filtering the capacitor value can be increased. Vendor Murata Recommended input capacitor LQH32CN100K53L SH30184R7YSB SH3018100YSB 10 4.7 10 Murata Part No. Value Vender GRM188R60J475KE19D 4.7µF/X5R/ Murata 0603/6.3V GRM219R60J106KE19D 10µF/X5R/ Murata 0805/6.3V ABC ABC Output capacitor selection Diode selection For better output voltage filtering, a low ESR output capacitor is recommended. Ceramic capacitors have a low ESR value, but depending on the application, tantalum capacitors can be used. The selection of the output capacitor value directly influences the output voltage ripple of the converter which also influences line regulation. The larger the output voltage ripple, the larger the line regulation, which means that the LED current changes if the input voltage changes. If a certain change in LED current gives a noticeable change in LED brightness, depends on the LED manufacturer and on the application. Applications requiring good line regulation ±1%/V (typ) must use output ca- To achieve high efficiency a Schottky diode must be used. The current rating of the diode must meet the peak current rating of the converter. Recommended diode Part No. MSCD052 Rev. A.1 - Feb., 2006 Vender Zowie Layout considerations Typical for all switching power supplies, the layout is an important step in the design; especially at high peak currents and switching frequencies. If the layout is not carefully done, the regulator might show noise problems and duty cycle jitter. The input capacitor should be placed as close as possible to the input pin for good input voltage filtering. The inductor and diode should be placed as close as possible to the switch pacitor values eqµAl or large than 1 µF. Copyright ANPEC Electronics Corp. Reverse Voltage 20 10 www.anpec.com.tw APW7071 Application Information (Cont.) Layout considerations (Conts.)() pin to minimize the noise coupling into other circuits. Since the feedback pin and network is a high impedance circuit, the feedback network should be routed away from the inductor. The feedback pin and feedback network should be shielded with a ground plane or trace to minimize noise coupling into this circuit. Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 11 www.anpec.com.tw APW7071 Package Information SOT-23-6 D 6 5 4 E 1 2 H 3 S1 e D A α A2 A1 Dim A A1 A2 b D E e H L L1 L2 α S1 Millimeters Min. 1.00 0.00 0.70 0.35 2.70 1.40 Max. 1.45 0.15 1.25 0.55 3.10 1.80 1.90 BSC 2.60 0.30 0.08 3.00 0.25 0.60 REF 0° 0.85 Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 L2 10 ° 1.05 12 L1 L Inches Min. Max. 0.0394 0.0571 0.0000 0.0591 0.0276 0.0492 0.0138 0.0217 0.1063 0.1220 0.50551 0.0709 0.07480 BSC 0.1024 0.1181 000118 0.0031 0.0098 0.024 REF 0° 10 ° 0.0335 0.0413 www.anpec.com.tw APW7071 Physical Specifications Terminal Material Lead Solderability Solder-Plated Copper (Solder Material : 90/10 or 63/37 SnPb) Meets EIA Specification RSI86-91, ANSI/J-STD-002 Category 3. Reflow Condition (IR/Convection or VPR Reflow) tp TP Critical Zone T L to T P Temperature Ramp-up TL tL Tsmax Tsmin Ramp-down ts Preheat 25 t 25 °C to Peak Time Classificatin Reflow Profiles Profile Feature Average ramp-up rate (TL to TP) Preheat - Temperature Min (Tsmin) - Temperature Max (Tsmax) - Time (min to max) (ts) Time maintained above: - Temperature (T L) - Time (tL) Peak/Classificatioon Temperature (Tp) Time within 5°C of actual Peak Temperature (tp) Ramp-down Rate Sn-Pb Eutectic Assembly Pb-Free Assembly 3°C/second max. 3°C/second max. 100°C 150°C 60-120 seconds 150°C 200°C 60-180 seconds 183°C 60-150 seconds 217°C 60-150 seconds See table 1 See table 2 10-30 seconds 20-40 seconds 6°C/second max. 6°C/second max. 6 minutes max. 8 minutes max. Time 25°C to Peak Temperature Notes: All temperatures refer to topside of the package .Measured on the body surface. Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 13 www.anpec.com.tw APW7071 Classificatin Reflow Profiles(Cont.) Table 1. SnPb Entectic Process – Package Peak Reflow Temperature s Package Thickness Volume mm 3 Volume mm 3 <350 ≥350 <2.5 mm 240 +0/-5°C 225 +0/-5°C ≥2.5 mm 225 +0/-5°C 225 +0/-5°C Table 2. Pb-free Process – Package Classification Reflow Temperatures Package Thickness Volume mm 3 Volume mm 3 Volume mm 3 <350 350-2000 >2000 <1.6 mm 260 +0°C* 260 +0°C* 260 +0°C* 1.6 mm – 2.5 mm 260 +0°C* 250 +0°C* 245 +0°C* ≥2.5 mm 250 +0°C* 245 +0°C* 245 +0°C* *Tolerance: The device manufacturer/supplier shall assure process compatibility up to and including the stated classification temperature (this means Peak reflow temperature +0°C. For example 260°C+0°C) at the rated MSL level. Reliability test program Test item SOLDERABILITY HOLT PCT TST ESD Latch-Up Method MIL-STD-883D-2003 MIL-STD-883D-1005.7 JESD-22-B, A102 MIL-STD-883D-1011.9 MIL-STD-883D-3015.7 JESD 78 Description 245°C , 5 SEC 1000 Hrs Bias @ 125 °C 168 Hrs, 100 % RH , 121°C -65°C ~ 150°C, 200 Cycles VHBM > 2KV, VMM > 200V 10ms , Itr > 100mA Carrier Tape t D P Po E P1 Bo F W Ko Ao Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 D1 14 www.anpec.com.tw APW7071 Carrier Tape(Cont.) T2 J C A B T1 Application SOT-23-5/6 A B C J 178 ±1 72 ± 1.0 F D D1 Po 3.5 ± 0.05 1.5± 0.1 1.5± 0.1 4.0 ± 0.1 13.0 + 0.2 2.5 ± 0.15 T1 T2 W P E 8.4 ± 2 1.5 ± 0.3 8.0 ± 0.3 4 ± 0.1 1.75± 0.1 P1 Ao Bo Ko t 3.2± 0.1 1.4± 0.1 0.2±0.033 2.0 ± 0.1 3.15 ± 0.1 (mm) Cover Tape Dimensions Application SOT- 23-5/6 Carrier Width 8 Cover Tape Width 5.3 Devices Per Reel 3000 Customer Service Anpec Electronics Corp. Head Office : No.6, Dusing 1st Road, SBIP, Hsin-Chu, Taiwan, R.O.C. Tel : 886-3-5642000 Fax : 886-3-5642050 Taipei Branch : 7F, No. 137, Lane 235, Pac Chiao Rd., Hsin Tien City, Taipei Hsien, Taiwan, R. O. C. Tel : 886-2-89191368 Fax : 886-2-89191369 Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2006 15 www.anpec.com.tw